Unpack/Packing Rockchip Firmware

Rockchip Firmware Format

The rockchip firmware "release_update.img", contains the boot loader
"loader.img" and the real firmware data "update.img":

release_update.img

   |- loader.img
   `- update.img

"update.img" is packed with multiple image files, described by a
control file named "package-file". A typical "package-file" is:

   # NAME Relative path
   package-file    package-file
   bootloader      Image/MiniLoaderAll.bin
   parameter       Image/parameter.txt
   trust           Image/trust.img
   uboot           Image/uboot.img
   misc            Image/misc.img
   resource        Image/resource.img
   kernel          Image/kernel.img
   boot            Image/boot.img
   recovery        Image/recovery.img
   system          Image/system.img
   backup          RESERVED
   #update-script  update-script
   #recover-script recover-script

package-file: packing description of update.img, which is also
included by update.img.

Image/MiniLoaderAll.bin: The first bootloader loaded by cpu rom code.

Image/parameter.txt: Parameter file where you can set the kernel boot
parameters and partition layout.

Image/trust.img: The Arm Trusted Image.

Image/misc.img: misc partition image, used to control boot mode of
Android.

Image/kernel.img: Android kernel image.

Image/resource.img: Resource image with boot logo and kernel device
tree blob.

Image/boot.img: Android initramfs, a root filesystem loaded in normal
boot, contains important initialization and services description.

Image/recovery.img: Recovery mode image.

Image/system.img: Android system partition image.

Unpacking is extracting "update.img" from "release_update.img",  and
then unpacking all the image files inside.

While repacking, it is the inverse process. It synthesizes the image
files described by the "package-file", into "update.img", which will
be further packed together with the bootloader to create the final
"release_update.img".

Installation of Tools

   git clone https://github.com/TeeFirefly/rk2918_tools.git
   cd rk2918_tools
   make
   sudo cp afptool img_unpack img_maker mkkrnlimg /usr/local/bin

Unpacking Rockchip Firmware

Unpacking release_update.img:  $ cd /path/to/your/firmware/dir $
img_unpack Firefly-RK3399_20161027.img img rom version: 6.0.1 build
time: 2016-10-27 14:58:18 chip: 33333043 checking md5sum....OK

Unpacking update.img:  $ cd img $ afptool -unpack update.img update
Check file...OK ------- UNPACK ------- package-file
0x00000800    0x00000280 Image/MiniLoaderAll.bin  0x00001000
0x0003E94E Image/parameter.txt      0x00040000    0x00000350
Image/trust.img          0x00040800    0x00400000 Image/uboot.img
0x00440800    0x00400000 Image/misc.img           0x00840800
0x0000C000 Image/resource.img       0x0084C800    0x0003FE00
Image/kernel.img         0x0088C800    0x00F5D00C Image/boot.img
0x017EA000    0x0014AD24 Image/recovery.img       0x01935000
0x013C0000 Image/system.img         0x02CF5000    0x2622A000 RESERVED
0x00000000    0x00000000 UnPack OK!

Check the file tree in the update directory:  $ cd update/ $ tree .
├── Image │   ├── boot.img │   ├── kernel.img │   ├──
MiniLoaderAll.bin │   ├── misc.img │   ├── parameter.txt │   ├──
recovery.img │   ├── resource.img │   ├── system.img │   ├── trust.img
│   └── uboot.img ├── package-file └── RESERVED  1 directory, 12 files

Packing Rockchip Firmware

First of all, make sure "system" partition in "parameter.txt" file is
larger enough to hold "system.img". You can reference

Parameter file format

 to understand the partition layout.

For example, in the line prefixed with "CMDLINE" in "parameter.txt",
you will find the description of "system" partition similiar to the
following content:

   0x00200000@0x000B0000(system)

The heximal string before the "@" is the partiton size in sectors (1
sector = 512 bytes here), therefore the size of the system partition
is:

   $ echo $(( 0x00200000 * 512 / 1024 / 1024 ))M
   1024M

To create "release_update_new.img":

   # The current directory is still update/, which contains package-file,
   # and files that package-file lists still exist
   # Copy the parameter file to paramter, because afptool is used by default

   $ afptool -pack . ../update_new.img
   ------ PACKAGE ------
   Add file: ./package-file
   Add file: ./Image/MiniLoaderAll.bin
   Add file: ./Image/parameter.txt
   Add file: ./Image/trust.img
   Add file: ./Image/uboot.img
   Add file: ./Image/misc.img
   Add file: ./Image/resource.img
   Add file: ./Image/kernel.img
   Add file: ./Image/boot.img
   Add file: ./Image/recovery.img
   Add file: ./Image/system.img
   Add file: ./RESERVED
   Add CRC...
   ------ OK ------
   Pack OK!

   $ img_maker -rk33 loader.img update_new.img release_update_new.img
   generate image...
   append md5sum...
   success!

Customization

Customizing system.img

system.img is an ext4 file system format image file which can be
mounted directly to the system for modification:

   sudo mkdir -p /mnt/system
   sudo mount Image/system.img /mnt/system
   cd /mnt/system
   # Modify the contents of the inside.
   # Pay attention to the free space,
   # You can not add too many APKs

   # When finished, you need to unmount it
   cd /
   sudo umount /mnt/system

Note that the free space of "system.img" is almost 0. If you need to
expand the image file, do adjust the partition layout in
"parameter.txt" accordingly.

The following is an example of how to increase the size of the image
file by 128MB.

Before expanding, make sure "system.img" is not mounted by running:

   mount | grep system

Resize the image file:

   dd if=/dev/zero bs=1M count=128 >> Image/system.img
   # Expand file system information
   e2fsck -f Image/system.img
   resize2fs Image/system.img